The present invention relates to a three-dimensional image display system for performing a display by means of binocular stereoscopic imaging with which a stereoscopic effect is obtained by utilizing a binocular parallax.
Binocular stereoscopic imaging for obtaining a stereoscopic effect by utilizing a binocular parallax allows three-dimensional recognition of image data in the following manner. A two-dimensional image of a three-dimensional object as would be seen by an observer's right eye and another two-dimensional image as would be seen by the observer's left eye are obtained, and this pair of images are selectively supplied to the right and left eyes of the observer. Various techniques for displaying a pair of right and left images and selectively supplying them to the right and left eyes of the observer are used. For example, the following techniques are known:
(a) A pair of right and left images are displayed on a pair of two-dimensional displays or are divisionally displayed on right and left screens of a single two-dimensional display. These display images are supplied independently to the right and left eyes of the observer through a stereoscopic viewer consisting of a pair of optical systems.
(b) A pair of right and left images are displayed in different display colors on a single two-dimensional display so as to be superposed on each other. The images are observed through filter spectacles comprising filters which are colored so that only the images corresponding to the appropriately designated eyes can be seen.
(c) Polarization filters having polarization axes which are perpendicular to the front surfaces of a pair of two-dimensional displays for respectively displaying a pair of right and left images are arranged. Images passing through these polarization filters are synthesized using a half-mirror. The observer observes the synthesized image through polarization spectacles comprising appropriate polarization filters corresponding to the above polarization filters.
(d) A pair of right and left images are alternately displayed for one field or one frame on a single two-dimensional display (in a time-divisional manner). The observer observes the display images on the two-dimensional display through liquid-crystal shutter spectacles comprising liquid-crystal shutters which are alternately opened/closed in synchronism with the display timings of the right and left images.
(e) A pair of right and left images are projected by a pair of right and left projectors from one surface side of a double lenticular screen in which the rear surfaces of two lenticular sheets are bonded to each other to sandwich a diffusion transmission layer therebetween. A display image is observed from the other surface side.
The pair of images are images obtained by a pair of cameras arranged so as to be separated by a predetermined distance, or are images obtained before and after a single camera is moved appropriately.
When stereoscopy is performed in this manner, the position of the observer with respect to the display screen, i.e., a distance between the display screen and the observer and an angle from which the observer watches the display screen, are specified in advance when a pair of two-dimensional images are formed. When the observer watches the display screen from a position (distance and viewing angle) other than the specified position, i.e., those positions which are not appropriate for properly observing the display image, the observer experiences an unnatural stereoscopic effect or suffers from noticeable fatigue of the eyes.
In this manner, in the conventional three-dimensional image display system using binocular stereoscopic imaging, the appropriate viewing position for obtaining a stereoscopic effect is specified. Therefore, the effective observation position is considerably limited.